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United States Patent |
5,753,772
|
Laurich
,   et al.
|
May 19, 1998
|
Rubbery polymers with improved color stability
Abstract
There is a need for polymers which are utilized in automotive interiors
which offer good color stability as well as a high level of heat and
ultraviolet light resistance. It is particularly critical for polymers
which are utilized in making skin compounds for automotive instrument and
door panels to have excellent color stability as well as excellent heat
and ultraviolet light resistance. This invention discloses a rubbery
polymer which can be blended with polyvinyl chloride to make leathery
compositions having good color stability, heat resistance and ultraviolet
light resistance, said rubbery polymer being comprised of repeat units
which are derived from (a) butyl acrylate, or optionally a mixture of
butyl acrylate and 2-ethylhexyl acrylate containing up to about 40 percent
2-ethylhexyl acrylate, (b) at least one member selected from the group
consisting of methyl methacrylate, ethyl methacrylate, methyl acrylate and
ethyl acrylate, (c) acrylonitrile, (d) styrene, (e) a conjugated diene
monomer and (f) a crosslinking agent; wherein the repeat units which are
derived from the conjugated diene monomer are epoxidized. Such leathery
compositions offer an excellent combination of properties for utilization
in making skin compounds for panels used in automotive applications.
Inventors:
|
Laurich; Jaclyn Beth (Tallmadge, OH);
Burroway; Gary Lee (Doylestown, OH);
Horvath; James Walter (Cuyahoga Falls, OH)
|
Assignee:
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The Goodyear Tire & Rubber Company (Akron, OH)
|
Appl. No.:
|
895652 |
Filed:
|
July 17, 1997 |
Current U.S. Class: |
525/329.3; 524/523; 524/561; 525/528; 526/329.1 |
Intern'l Class: |
C08F 036/00; C08F 220/12 |
Field of Search: |
526/146,94,329.1
525/329.3,528
524/523,561
|
References Cited
U.S. Patent Documents
2414803 | Jan., 1947 | D'Alelio | 526/329.
|
3198854 | Aug., 1965 | Warner | 526/329.
|
3354238 | Nov., 1967 | Schmitt et al. | 526/329.
|
3400175 | Sep., 1968 | Firestone et al. | 526/329.
|
3792125 | Feb., 1974 | Wefer | 526/329.
|
4000359 | Dec., 1976 | Watts et al. | 526/329.
|
4229549 | Oct., 1980 | Usami et al. | 526/329.
|
4268549 | May., 1981 | Fink et al. | 526/329.
|
4319015 | Mar., 1982 | Struver et al. | 526/329.
|
5380785 | Jan., 1995 | Ngoc et al.
| |
Foreign Patent Documents |
52-54689 | May., 1977 | JP | 526/329.
|
60-94413 | May., 1985 | JP | 526/329.
|
Other References
Journal of Polymer Science, Polymer Chemistry Edition No. 12 vol. 15 (1977)
pp. 3079-3080.
|
Primary Examiner: Schofer; Joseph L.
Assistant Examiner: Sarofim; N.
Attorney, Agent or Firm: Rockhill; Alvin T.
Claims
What is claimed is:
1. A rubbery polymer which can be blended with polyvinyl chloride to make
leathery compositions having good color stability, heat resistance and
ultraviolet light resistance, said rubbery polymer being comprised of
repeat units which are derived from (a) butyl acrylate, or optionally a
mixture of butyl acrylate and 2-ethylhexyl acrylate containing up to about
40 percent 2-ethylhexyl acrylate, (b) at least one member selected from
the group consisting of methyl methacrylate, ethyl methacrylate, methyl
acrylate and ethyl acrylate, (c) acrylonitrile, (d) styrene, (e) a
conjugated diene monomer and (f) a crosslinking agent; wherein the repeat
units which are derived from the conjugated diene monomer are epoxidized.
2. A process for preparing a rubbery polymer which can be blended with
polyvinyl chloride to make leathery compositions having improved color
stability as well as good heat and ultraviolet light resistance, said
process comprising the steps of (1) polymerizing (a) butyl acrylate, or
optionally a mixture of butyl acrylate and 2-ethylhexyl acrylate
containing up to about 40 percent 2-ethylhexyl acrylate, (b) at least one
member selected from the group consisting of methyl methacrylate, ethyl
methacrylate, methyl acrylate and ethyl acrylate, (c) acrylonitrile, (d) a
conjugated diolefin monomer and (e) a crosslinking agent under emulsion
polymerization conditions to produce a seed polymer containing latex; (2)
adding (a) styrene, (b) additional acrylonitrile, (c) additional
conjugated diolefin monomer and (d) additional crosslinking agent to the
seed polymer containing latex under emulsion polymerization conditions
which result in the formation of an emulsion containing the rubbery
polymer; (3) epoxidizing the rubbery polymer; and (4) recovering the
rubbery polymer from the emulsion containing the rubbery polymer.
3. A leathery composition which is useful in automotive applications which
is comprised of (1) polyvinyl chloride, (2) a plasticizer and (3) a
rubbery polymer which is comprised of repeat units which are comprised of
(a) butyl acrylate, or optionally a mixture of butyl acrylate and
2-ethylhexyl acrylate containing up to about 40 percent 2-ethylhexyl
acrylate, (b) at least one member selected from the group consisting of
methyl methacrylate, ethyl methacrylate, methyl acrylate and ethyl
acrylate, (c) acrylonitrile, (d) styrene, (e) a conjugated diolefin
monomer and (f) a crosslinking agent, wherein the rubbery polymer is
epoxidized.
4. A leathery composition which is useful in automotive applications which
is comprised of (1) polyvinyl chloride, (2) a plasticizer and (3) a
rubbery polymer which is comprised of repeat units which are comprised of
(a) butyl acrylate, or optionally a mixture of butyl acrylate and
2-ethylhexyl acrylate containing up to about 40 percent 2-ethylhexyl
acrylate, (b) at least one member selected from the group consisting of
methyl methacrylate, ethyl methacrylate, methyl acrylate and ethyl
acrylate, (c) acrylonitrile, (d) styrene, (e) a conjugated diolefin
monomer and (f) a crosslinking agent, wherein the rubbery polymer is
ozonated.
5. The rubbery polymer specified in claim 1 wherein the crosslinking agent
is selected from the group consisting of difunctional acrylates,
trifunctional acrylates, difunctional methacrylates, trifunctional
methacrylates and divinylbenzene.
6. A process as specified in claim 2 wherein the crosslinking agent
utilized in step (1) is 1,4-butanediol dimethacrylate; and wherein the
crosslinking agent utilized in step (2) is divinylbenzene.
7. A process as specified in claim 2 which further comprises drying the
rubbery polymer recovered from the emulsion and subsequently converting it
into a powder.
8. A process as specified in claim 7 wherein the rubbery polymer is
converted to a powder in the presence of a partitioning agent.
9. A process as specified in claim 8 wherein the partitioning agent is
selected from the group consisting of calcium carbonate, emulsion
polyvinyl chloride and silica.
10. A process as specified in claim 2 wherein 2-ethylhexyl acrylate is
further polymerized in an amount up to 40 weight percent of the total
amount of butyl acrylate and 2-ethylhexyl acrylate polymerized.
11. A process as specified in claim 2 wherein the emulsion containing the
rubbery polymer is epoxidized in step (3) by adding formic acid, hydrogen
peroxide and acetic acid to the emulsion containing the rubbery polymer.
Description
BACKGROUND OF THE INVENTION
Automotive instrument panels and door panels are typically composites which
are made of a rigid backing which supports a semi-rigid urethane foam with
the semi-rigid urethane foam being covered with a skin compound. Such skin
compounds are typically blends of polyvinyl chloride (PVC) with a nitrile
rubber (NBR). The nitrile rubber is included in such blends as a permanent
modifier for the PVC which provides it with a higher degree of
flexibility.
The automotive industry is currently moving toward more aerodynamic body
designs. These new aerodynamic designs typically include larger glass
surface areas. Such design changes have significantly increased the heat
and ultraviolet light aging requirements of automotive interiors. This
has, in turn, significantly increased the demands put upon polymers
utilized as skins in automotive interior panels.
Heat and light stabilizers can be employed to improve the heat and
ultraviolet light aging characteristics of conventional PVC/NBR blends
which are utilized as skins for automotive interior panels. However, the
degree to which the aging characteristics of such blends can be improved
by the addition of additives is limited. In fact, there is a demand for
performance characteristics in such applications which cannot be realized
by the utilization of heat and light stabilizers alone. For instance, it
would be highly desirable for the skins used in automotive panels to
resist discoloration and cracking under conditions of high heat and
intense ultraviolet light throughout the life of the vehicle.
NBR/PVC blends offer an array of physical properties making them useful as
a skin composition for automotive panels. The NBR acts as a permanent
flexibilizing monomer for the PVC. It also acts as a shrinkage control
agent, and embossing aid, and improves grain retention. The NBR in such
blends further provides vacuum-forming gauge control and exhibits low fog
characteristics. NBR is highly compatible with PVC and has the capability
of being recycled. It is essential for any polymer that is substituted for
NBR to display these essential characteristics.
U.S. Pat. No. 5,380,785 discloses rubbery polymer which can be blended with
polyvinyl chloride to make leathery compositions having good heat and
ultraviolet light resistance, said rubbery polymer being comprised of
repeat units which are derived from (a) butyl acrylate, or optionally a
mixture of butyl acrylate and 2-ethylhexyl acrylate containing up to about
40 percent 2-ethylhexyl acrylate, (b) at least one member selected from
the group consisting of methyl methacrylate, ethyl methacrylate, methyl
acrylate and ethyl acrylate, (c) acrylonitrile, (d) styrene, (e) a half
ester maleate soap and (f) a crosslinking agent. However, it would be
highly desirable to increase the color stability of such rubbery polymers.
SUMMARY OF THE INVENTION
The present invention relates to a rubbery polymer that can be blended with
PVC to make leathery compositions. These compositions are particularly
useful in manufacturing skins for automotive interior panels. Skin
compositions that are made utilizing this rubbery polymer provide a higher
level of resistance to heat and ultraviolet light than those made
utilizing conventional NBR/PVC blends. They also offer greatly improved
color stability. The rubbery polymers of this invention also offer low fog
characteristics, low odor, shrinkage control and grain retention. They
also act as an embossing aid and as a permanent flexibilizing modifier.
The rubbery polymers of this invention also have characteristics that make
them useful in building gasket applications.
This invention more specifically discloses a rubbery polymer which can be
blended with polyvinyl chloride to make leathery compositions having good
color stability, heat resistance and ultraviolet light resistance, said
rubbery polymer being comprised of repeat units which are derived from (a)
butyl acrylate, or optionally a mixture of butyl acrylate and 2-ethylhexyl
acrylate containing up to about 40 percent 2-ethylhexyl acrylate, (b) at
least one member selected from the group consisting of methyl
methacrylate, ethyl methacrylate, methyl acrylate and ethyl acrylate, (c)
acrylonitrile, (d) styrene, (e) a conjugated diene monomer and (f) a
crosslinking agent; wherein the repeat units which are derived from the
conjugated diene monomer are epoxidized.
The subject invention further reveals a process for preparing a rubbery
polymer which can be blended with polyvinyl chloride to make leathery
compositions having improved color stability as well as good heat and
ultraviolet light resistance, said process comprising the steps of (1)
polymerizing (a) butyl acrylate, or optionally a mixture of butyl acrylate
and 2-ethylhexyl acrylate containing up to about 40 percent 2-ethylhexyl
acrylate, (b) at least one member selected from the group consisting of
methyl methacrylate, ethyl methacrylate, methyl acrylate and ethyl
acrylate, (c) acrylonitrile, (d) a conjugated diolefin monomer and (e) a
crosslinking agent under emulsion polymerization conditions to produce a
seed polymer containing latex; (2) adding (a) styrene, (b) additional
acrylonitrile, (c) additional conjugated diolefin monomer and (d)
additional crosslinking agent to the seed polymer containing latex under
emulsion polymerization conditions which result in the formation of an
emulsion containing the rubbery polymer; (3) epoxidizing the rubbery
polymer; and (4) recovering the rubbery polymer from the emulsion
containing the rubbery polymer.
The subject invention further reveals a process for preparing a rubbery
polymer which can be blended with polyvinyl chloride to make leathery
compositions having improved tensile properties as well as good heat and
ultraviolet light resistance, said process comprising the steps of (1)
polymerizing (a) butyl acrylate, or optionally a mixture of butyl acrylate
and 2-ethylhexyl acrylate containing up to about 40 percent 2-ethylhexyl
acrylate, (b) at least one member selected from the group consisting of
methyl methacrylate, ethyl methacrylate, methyl acrylate and ethyl
acrylate, (c) acrylonitrile, (d) a conjugated diolefin monomer and (e) a
crosslinking agent under emulsion polymerization conditions to produce a
seed polymer containing latex; (2) adding (a) styrene, (b) additional
acrylonitrile, (c) additional conjugated diolefin monomer and (d)
additional crosslinking agent to the seed polymer containing latex under
emulsion polymerization conditions which result in the formation of an
emulsion containing the rubbery polymer; (3) ozonating the rubbery
polymer; and (4) recovering the rubbery polymer from the emulsion
containing the rubbery polymer.
The present invention also discloses a leathery composition which is useful
in automotive applications which is comprised of (1) polyvinyl chloride,
(2) a plasticizer and (3) a rubbery polymer which is comprised of repeat
units which are comprised of (a) butyl acrylate, or optionally a mixture
of butyl acrylate and 2-ethylhexyl acrylate containing up to about 40
percent 2-ethylhexyl acrylate, (b) at least one member selected from the
group consisting of methyl methacrylate, ethyl methacrylate, methyl
acrylate and ethyl acrylate, (c) acrylonitrile, (d) styrene, (e) a
conjugated diolefin monomer and (f) a crosslinking agent, wherein the
rubbery polymer is epoxidized.
The subject invention further reveals a panel for automotive applications
which is comprised of a semirigid urethane foam which is supported by a
rigid backing, wherein said semirigid urethane foam is covered with a
leathery skin which is comprised of (1) polyvinyl chloride, (2) a
plasticizer and (3) a rubbery polymer which is comprised of repeat units
which are comprised of (a) butyl acrylate, or optionally a mixture of
butyl acrylate and 2-ethylhexyl acrylate containing up to about 40 percent
2-ethylhexyl acrylate, (b) at least one member selected from the group
consisting of methyl methacrylate, ethyl methacrylate, methyl acrylate and
ethyl acrylate, (c) acrylonitrile, (d) styrene, (e) a conjugated diolefin
monomer and (f) a crosslinking agent, wherein said rubbery polymer is
epoxidized.
The present invention also discloses a leathery composition which is useful
in automotive applications which is comprised of (1) polyvinyl chloride,
(2) a plasticizer and (3) a rubbery polymer which is comprised of repeat
units which are comprised of (a) butyl acrylate, or optionally a mixture
of butyl acrylate and 2-ethylhexyl acrylate containing up to about 40
percent 2-ethylhexyl acrylate, (b) at least one member selected from the
group consisting of methyl methacrylate, ethyl methacrylate, methyl
acrylate and ethyl acrylate, (c) acrylonitrile, (d) styrene, (e) a
conjugated diolefin monomer and (f) a crosslinking agent, wherein the
rubbery polymer is ozonated.
The subject invention further reveals a panel for automotive applications
which is comprised of a semirigid urethane foam which is supported by a
rigid backing, wherein said semirigid urethane foam is covered with a
leathery skin which is comprised of (1) polyvinyl chloride, (2) a
plasticizer and (3) a rubbery polymer which is comprised of repeat units
which are comprised of (a) butyl acrylate, or optionally a mixture of
butyl acrylate and 2-ethylhexyl acrylate containing up to about 40 percent
2-ethylhexyl acrylate, (b) at least one member selected from the group
consisting of methyl methacrylate, ethyl methacrylate, methyl acrylate and
ethyl acrylate, (c) acrylonitrile, (d) styrene, (e) a conjugated diolefin
monomer and (f) a crosslinking agent, wherein said rubbery polymer is
ozonated.
DETAILED DESCRIPTION OF THE INVENTION
The rubbery polymers of this invention are synthesized utilizing a free
radical emulsion polymerization technique. These rubbery polymers are
comprised of repeat units which are derived from (a) butyl acrylate, or
optionally a mixture of butyl acrylate and 2-ethylhexyl acrylate
containing up to about 40 percent 2-ethylhexyl acrylate, (b) methyl
methacrylate, ethyl methacrylate, methyl acrylate or ethyl acrylate, (c)
acrylonitrile, (d) styrene, (e) a conjugated diolefin monomer and (f) a
crosslinking agent. The crosslinking agent is typically a multi-functional
acrylate, a multi-functional methacrylate or divinylbenzene. Some specific
examples of crosslinking agents which can be used include ethylene glycol
methacrylate, divinylbenzene and 1,4-butanediol dimethacrylate.
Technically, the rubbery polymers of this invention contain repeat units
(chain linkages) which are derived from (a) butyl acrylate, or optionally
a mixture of butyl acrylate and 2-ethylhexyl acrylate containing up to
about 40 percent 2-ethylhexyl acrylate, (b) methyl methacrylate, ethyl
methacrylate, methyl acrylate or ethyl acrylate, (c) acrylonitrile, (d)
styrene, (e) a conjugated diolefin monomer and (f) a crosslinking agent.
These repeat units differ from the monomers that they were derived from in
that they contain one less carbon-carbon double bond than is present in
the respective monomer. In other words, a carbon-to-carbon double bond is
consumed during the polymerization of the monomer into a repeat unit in
the rubbery polymer. Thus, in saying that the rubbery polymer contains
various monomers, in actuality means that it contains repeat units that
are derived from those monomers.
The rubbery polymers of this invention will normally contain (a) from about
40 weight percent to about 80 weight percent butyl acrylate, or optionally
a mixture of butyl acrylate and 2-ethylhexyl acrylate containing up to 40
weight percent 2-ethylhexyl acrylate, (b) from about 3 weight percent to
about 35 weight percent methyl methacrylate, ethyl methacrylate, methyl
acrylate or ethyl acrylate, (c) from about 4 weight percent to about 30
weight percent acrylonitrile, (d) from about 3 weight percent to about 25
weight percent styrene, (e) from about 4 weight percent to about 20 weight
percent of a conjugated diolefin monomer and (f) from about 0.25 weight
percent to about 8 weight percent of a crosslinking agent.
Such rubbery polymers will preferably contain (a) from about 50 weight
percent to about 77 weight percent butyl acrylate, or optionally a mixture
of butyl acrylate and 2-ethylhexyl acrylate containing up to about 40
percent 2-ethylhexyl acrylate, (b) from about 5 weight percent to about 25
weight percent of at least one member selected from the group consisting
of methyl methacrylate, ethyl methacrylate, methyl acrylate and ethyl
acrylate, (c) from about 5 weight percent to about 30 weight percent
acrylonitrile, (d) from about 5 weight percent to about 18 weight percent
styrene, (e) from about 6 weight percent to about 16 weight percent of a
conjugated diolefin monomer and (f) from about 0.5 weight percent to about
4 weight percent of a crosslinking agent.
The rubbery polymers of this invention will more preferably be comprised of
repeat units which are derived from (a) about 55 weight percent to about
75 weight percent butyl acrylate, or optionally a mixture of butyl
acrylate and 2-ethylhexyl acrylate containing up to about 40 percent
2-ethylhexyl acrylate, (b) about 5 weight percent to about 20 weight
percent of at least one member selected from the group consisting of
methyl methacrylate, ethyl methacrylate, methyl acrylate and ethyl
acrylate, (c) about 6 weight percent to about 20 weight percent
acrylonitrile, (d) about 6 weight percent to about 14 weight percent
styrene, (e) about 7 weight percent to about 14 weight percent of a
conjugated diolefin monomer and (f) about 1 weight percent to about 3
weight percent of a crosslinking agent. The percentages reported in this
paragraph are based upon the total weight of the rubbery polymer.
The rubbery polymers of the present invention are synthesized in an aqueous
reaction mixture by utilizing a free radical polymerization technique. The
reaction mixture utilized in this polymerization technique is comprised of
water, the appropriate monomers, a suitable free radical initiator, a
crosslinking agent and a soap. It is often preferred to utilize a metal
salt of an alkyl sulfonate or a metal salt of an alkyl sulfate as the
soap. The reaction mixture utilized in this polymerization technique will
normally contain from about 10 weight percent to about 80 weight percent
monomers, based upon the total weight of the reaction mixture. The
reaction mixture will preferably contain from about 20 weight percent to
about 70 weight percent monomers and will more preferably contain from
about 40 weight percent to about 50 weight percent monomers.
The reaction mixtures utilized in carrying out such polymerizations will
typically contain from about 0.005 phm (parts per hundred parts of monomer
by weight) to about 1 phm of at least one member selected from the group
consisting of metal salts of alkyl sulfates and metal salts of alkyl
sulfonates. It is generally preferred for the reaction mixture to contain
from about 0.008 phm to about 0.5 phm of the metal salt of the alkyl
sulfonate or the metal salt of the alkyl sulfate. It is normally more
preferred for the reaction mixture to contain from about 0.05 phm to about
0.3 phm of the metal salt of the alkyl sulfonate or the metal salt of the
alkyl sulfate.
The free radical polymerization technique utilized in this synthesis is
normally initiated by including a free radical initiator in the reaction
mixture. Virtually, any type of compound capable of generating free
radicals can be utilized as the free radical initiator. The free radical
generator is normally employed at a concentration within the range of
about 0.01 phm to about 1 phm. The free radical initiators which are
commonly used include the various peroxygen compounds such as potassium
persulfate, ammonium persulfate, benzoyl peroxide, hydrogen peroxide,
di-t-butyl peroxide, dicumyl peroxide, 2,4-dichlorobenzoyl peroxide,
decanoyl peroxide, lauryl peroxide, cumene hydroperoxide, p-menthane
hydroperoxide, t-butyl hydroperoxide, acetyl peroxide, methyl ethyl ketone
peroxide, succinic acid peroxide, dicetyl peroxydicarbonate, t-butyl
peroxyacetate, t-butyl peroxymaleic acid, t-butyl peroxybenzoate, acetyl
cyclohexyl sulfonyl peroxide, and the like; the various azo compounds such
as 2-t-butylazo-2-cyanopropane, dimethyl azodiisobutyrate,
azodiisobutylronitrile, 2-t-butylazo-1-cyanocyclohexane,
1-t-amylazo-1-cyanocyclohexane, and the like, the various alkyl perketals,
such as 2,2-bis-(t-butyl-peroxy)butane, and the like. Water-soluble
peroxygen-free radical initiators are especially useful in such aqueous
polymerizations.
The emulsion polymerizations of this invention are typically carried out at
the temperature which is within the range of about 10.degree. C. to about
95.degree. C. At temperatures above about 88.degree. C., alkyl acrylate
monomers (such as butyl acrylate) have a tendency to boil. Thus, a
pressurized jacket would be required for heating such alkyl acrylate
monomers to temperatures in excess of about 80.degree. C. Thus, in most
cases, the polymerization temperature utilized will vary between about
20.degree. C. and about 80.degree. C. On the other hand, at polymerization
temperatures of less than about 55.degree. C., a redox initiator system is
required to insure satisfactory polymerization rates.
The sulfonate surfactants that are useful in this invention are
commercially available from a wide variety of sources. For instance, Du
Pont sells sodium alkylarylsulfonate under the tradename Alkanol.TM.,
Browning Chemical Corporation sells sodium dodecylbenzene sulfonates under
the tradename Ufaryl.TM. D1-85 and Ruetgers-Nease Chemical Company sells
sodium cumene sulfonate under the tradename Naxonate Hydrotrope.TM.. Some
representative examples of sulfonate surfactants which can be used include
sodium toluene-xylene sulfonate, sodium toluene sulfonate, sodium cumene
sulfonates, sodium decyldiphenylether sulfonate, sodium
dodecylbenzenesulfonate, sodium dodecyldiphenylether sulfonate, sodium
1-octane sulfonate, sodium tetradecane sulfonate, sodium pentadecane
sulfonate, sodium heptadecane sulfonate and potassium toluene sulfonate.
Metal salts of alkylbenzene sulfonates are a highly preferred class of
sulfonate surfactant. The metal will generally be sodium or potassium with
sodium being preferred. Sodium salts of alkylbenzene sulfonates have the
structural formula:
##STR1##
wherein R represents an alkyl group containing from 1 to about 20 carbon
atoms. It is preferred for the alkyl group to contain from about 8 to
about 14 carbon atoms.
The polymerization is carried out as a two-step batch process. In the first
step, a seed polymer containing latex is synthesized. This is done by
polymerizing (a) butyl acrylate, or optionally a mixture of butyl acrylate
and 2-ethylhexyl acrylate containing up to about 40 percent 2-ethylhexyl
acrylate, (b) at least one member selected from the group consisting of
methyl methacrylate, ethyl methacrylate, methyl acrylate and ethyl
acrylate, (c) acrylonitrile, (d) a conjugated diolefin monomer and (d) a
crosslinking agent.
The seed polymer containing latex is typically prepared by the
polymerization of a monomer mixture which contains about 40 to about 90
weight percent butyl acrylate, or optionally a mixture of butyl acrylate
and 2-ethylhexyl acrylate containing up to about 40 percent 2-ethylhexyl
acrylate, from about 1 to about 35 weight percent methyl methacrylate,
ethyl methacrylate, methyl acrylate or ethyl acrylate, from about 2 to
about 30 weight percent acrylonitrile, from about 2 to about 30 weight
percent of a conjugated diolefin monomer and from about 0.25 weight
percent to 6 weight percent of the crosslinking agent. It is typically
preferred for the monomeric component utilized in the first step to
include about 50 weight percent to about 85 weight percent butyl acrylate
or optionally a mixture of butyl acrylate and 2-ethylhexyl acrylate
containing up to about 40 percent 2-ethylhexyl acrylate, from about 2
weight percent to about 20 weight percent ethyl acrylate, ethyl
methacrylate, methyl acrylate or methyl methacrylate, from about 4 weight
percent to about 28 weight percent acrylonitrile, from about 4 weight
percent to about 25 weight percent of a conjugated diolefin monomer and
from about 0.25 weight percent to about 4 weight percent of the
crosslinking agent. It is generally more preferred for the monomer charge
composition used in synthesizing the seed polymer latex to contain from
about 60 weight percent to about 80 weight percent butyl acrylate, or
optionally a mixture of butyl acrylate and 2-ethylhexyl acrylate
containing up to about 40 percent 2-ethylhexyl acrylate, from about 3
weight percent to about 20 weight percent methyl methacrylate, ethyl
methacrylate, methyl acrylate or ethyl acrylate, from about 5 weight
percent to about 20 weight percent acrylonitrile, from about 6 weight
percent to about 20 weight percent of a conjugated diolefin monomer and
from about 0.25 weight percent to about 2 weight percent crosslinking
agent.
After the seed polymer latex has been prepared, styrene monomer, additional
acrylonitrile monomer, additional conjugated diolefin monomer and
additional crosslinking agent is added to the seed polymer containing
latex. As a general rule, from about 5 parts by weight to about 80 parts
by weight of styrene, from about 5 part by weight to about 50 parts by
weight of additional acrylonitrile, from about 2 parts by weight to about
40 parts by weight of additional conjugated diolefin monomer and from
about 0.25 to 15 parts by weight of the crosslinking agent will be added.
In this second stage of the polymerization, it is preferred to add from
about 20 parts by weight to about 75 parts by weight of styrene, from
about 15 parts by weight to about 40 parts by weight of acrylonitrile,
from about 4 parts by weight to about 30 parts by weight of conjugated
diolefin monomer and from about 1 part by weight to 10 part by weight of
the crosslinking agent. It is typically more preferred for from about 50
parts by weight to about 70 parts by weight of styrene, from about 20
parts by weight to about 35 parts by weight of acrylonitrile, from about 5
parts by weight to about 20 parts by weight of conjugated diolefin monomer
and from about 3 parts by weight to about 7 parts by weight of the
crosslinking agent to be added to the seed polymer latex to initiate the
second phase of the polymerization.
A wide variety of crosslinking agents can be utilized in carrying out the
polymerizations of this invention. Some representative examples of
crosslinking agents that can be utilized include difunctional acrylates,
difunctional methacrylates, trifunctional acrylates, trifunctional
methacrylates and divinylbenzene. The crosslinking agent proven to be
particularly useful is 1,4-butanediol dimethacrylate. The conjugated
diolefin monomers that can be employed will typically contain from 4 to
about 8 carbon atoms. Isoprene and 1,3-butadiene are preferred conjugated
diolefin monomers with 1,3-butadiene being the most preferred.
In most cases, the polymerization will be continued until a high monomer
conversion has been attained. After the polymerization has been completed,
the rubbery polymer will be epoxidized to improve color stability or
ozonated to improve tensile properties. The rubbery polymer can, of
course, be both epoxidized and ozonated to improve both of these
characteristics. In any case, the rubbery polymer is epoxidized and/or
ozonated while it is still in the emulsion.
The rubbery polymer can be epoxidized by simply adding a peracid, such as
perbenzoic acid or performic acid, to the latex containing the rubbery
polymer. To insure that all of the double bonds in the rubbery polymer
undergo epoxidation, an excess of the peracid will normally be added. It
should be noted that one mole of double bonds will be present in the
rubbery polymer for every mole of conjugated diolefin monomer employed in
its synthesis.
It is normally convenient to form the peracid in situ in the latex of the
rubbery polymer. For instance, performic acid (methaneperoxoic acid) can
be generated in situ in the latex by reacting formic acid with hydrogen
peroxide. This reaction will typically be conducted in the presence of
acetic acid which acts as a catalyst. Thus, the epoxidation can
conveniently be done by adding formic acid, hydrogen peroxide and acetic
acid to the latex of the rubbery polymer. The epoxidation of the rubbery
polymer will typically be carried out at a temperature which is within the
range of about 70.degree. F. (21.degree. C.) to about 140.degree. F.
(60.degree. C.). It is normally preferred for the epoxidation to conducted
at a temperature which is within the range of about 90.degree. F.
(32.degree. C.) to about 130.degree. F. (54.degree. C.) with it being most
preferred for the epoxidation to be conducted at a temperature which is
within the range of about 110.degree. F. (43.degree. C.) to about
120.degree. F. (49.degree. C.).
The rubbery polymer can be ozonated by simply mixing ozone into the latex
of the rubbery polymer for a period of time which is sufficient to attain
the desired results. This can be accomplished by bubbling ozone through
the latex. It can also be done by rapidly agitating the latex under an
ozone containing atmosphere. It may be desirable for the ozone containing
atmosphere to be under pressure. Other techniques for mixing ozone
throughout the latex being treated can also be employed in practicing the
present invention.
The temperature at which this treatment procedure is carried out is not
critical. In fact, virtually any temperature between the freezing point of
the latex and its boiling point can be utilized. However, for practical
reasons, the latex will normally be treated with ozone at a temperature
which is within the range of about 0.degree. C. to about 60.degree. C. A
temperature within the range of about 15.degree. C. to about 30.degree. C.
will most preferably be employed. Higher temperatures can result in
reduced solubility of the ozone in the latex even though faster reaction
rates may be attained. The ozone treatment will be carried out for a time
which is sufficient to ozonate a sufficient number of double bonds in the
polymer to attain the tensile properties which are desired. The treatment
time employed will typically be within the range of about 15 minutes to
about 6 hours. The period of time utilized in treating the latex with
ozone will more typically be within the range of about 30 minutes to about
2 hours.
The reaction through which ozone cleaves the double bonds in the rubbery
polymer can be depicted as follows:
##STR2##
In the absence of zinc, hydrogen peroxide is formed which may degrade the
carbonyl products formed by oxidation. In such a scenario, the hydrogen
peroxide reacts with the aldehydes produced by ozonylsis and converts them
to carboxylic acids. A more detailed description of ozonolysis is provided
by J March, Advanced Organic Chemistry: Reactions, Mechanisms and
Structure; pages 871-874 (McGraw-Hill Book Company, 1968) and by R T
Morrison and R N Boyd, Organic Chemistry; Third Edition; pages 218-219
(Allyn and Bacon, Inc., 1973).
If the ozonylsis is carried out in the absence of zinc, carboxyl groups
will typically be formed. As the amount of carboxyl groups on the polymer
increases, the pH of the emulsion decreases. The extent to which double
bonds in the polymer have been cleaved can accordingly be monitored by
monitoring the pH of the emulsion.
After the epoxidation and/or ozonylsis step has been completed, it is
normally desirable to add an aminoalcohol to the emulsion to deodorize the
latex. The aminoalcohol will generally be of the structural formula
HO--A--NH.sub.2 wherein A represents an alkylene group which contains from
2 to about 20 carbon atoms. It is normally preferred for the aminoalcohol
to contain from 2 to about 10 carbon atoms with amino alcohols which
contain from 2 to about 5 carbon atoms being most preferred. Ethanolamine
(HO--CH.sub.2 --CH.sub.2 --NH.sub.2) which is also known as 2-aminoethanol
and 2-hydroxyethylamine is a representative example of a highly preferred
aminoalcohol. Some additional examples of preferred aminoalcohols include
3-aminopropanol, 4-aminobutanol, 2-amino-2-methyl-1-propanol,
2-amino-2-ethyl-1,3-propanediol, N-methyl-2,2-iminoethanol and
5-aminopentanol.
This deodorizing step will be carried out under conditions which allow for
the aminoalcohol to react with residual n-butylacrylate and acrylonitrile
which is present in the emulsion. This reaction will proceed over a broad
temperature range and the deodorizing step can be conducted at any
temperature which is within the range of about 5.degree. C. and about
95.degree. C. However, for practical reasons, the deodorizing step will
normally be carried out at a temperature which is within the range of
about 20.degree. C. to about 70.degree. C. Since the reaction is faster at
higher temperatures, the amount of reaction time needed will decrease with
increasing temperature. For instance, at a temperature of about 20.degree.
C., a residence time in the deodorizing step of one to three days may be
required. On the other hand, at a temperature of about 65.degree. C., only
about two hours of reaction time is normally required.
The amount of time required for the aminoalcohol to react with the residual
n-butylacrylate monomer and residual acrylonitrile monomer will also
depend upon the level of aminoalcohol utilized. As a general rule, from
about 0.05 weight percent to about 2 weight percent of the aminoalcohol
will be added, based upon the total weight of the emulsion. More typically
from about 0.1 weight percent to about 1.5 weight percent of the
aminoalcohol will be added. It is normally preferred to utilize from about
0.3 weight percent to about 1 weight percent of the aminoalcohol.
The rubbery polymer is recovered from the emulsion (latex) after the
optional deodorizing step. This can be accomplished by utilizing standard
coagulation techniques. For instance, coagulation can be accomplished by
the addition of salts, acids or both to the latex.
After the rubbery polymer is recovered by coagulation, it can be washed to
further reduce odors. This can be accomplished by simply pouring or
spraying water on the rubbery polymer. The rubbery polymer can also be
washed in a water bath. Such a washing step will, of course, further
reduce the level of any odor. After being washed, the rubbery polymer is
generally dried.
It is sometimes advantageous to convert the dry rubbery polymer into a
powder to facilitate its usage. In this case, it will be beneficial to add
a partitioning agent to the rubbery polymer. Some representative examples
of partitioning agents that can be employed include calcium carbonate,
emulsion polyvinyl chloride and silica. Calcium carbonate is a highly
desirable partitioning agent that can be utilized in such applications.
The rubbery polymers of this invention can be blended with
polyvinylchloride to make leather-like compositions. These leathery
compositions offer an excellent combination of properties for utilization
in making skin compounds for panels used in automotive applications. These
leathery compositions can be prepared by blending the rubbery polymer into
polyvinylchloride (PVC) utilizing standard mixing techniques. It is highly
preferred for the rubbery polymer to be in powdered form when blended into
PVC to make such leathery compositions.
A wide variety of plasticizers that are compatible with the polyvinyl
chloride resins can be employed. Some representative examples of
plasticizers which are highly suitable for this application include
abietic derivatives, such as hydroabietyl alcohol, methyl abietate and
hydrogenated methyl abietate; acetic acid derivatives, such as cumylphenyl
acetate; adipic acid derivatives, such as benzyloctyl adipate, dibutyl
adipate, diisobutyl adipate, di-(2-ethylhexyl) adipate, diisononyl
adipate, diisooctyl adipate, dinonyl adipate, C.sub.7-9 linear adipate,
dicapryl adipate, octyl decyl adipate (n-octyl, n-decyl adipate), straight
chain alcohol adipate, didecyl adipate (diisodecyl adipate), dibutoxyethyl
adipate, high molecular weight adipate, polypropylene adipate, modified
polypropylene adipate; azelaic acid derivatives, such as dicyclohexyl
azelate, di-(2-ethylhexyl) azelate, di-n-hexyl azelate, low temperature
plasticizer, diisooctyl azelate; benzoic acid derivatives such as
diethylene glycol dibenzoate, dipropylene glycol dibenzoate, diethylene
glycol benzoate and dipropylene glycol benzoate blend, proprietary low
stain, neopentyl glycol dibenzoate, glyceryl tribenzoate, timethylolethane
tribenzoate, pentaerythritol tribenzoate, cumylphenyl benzoate; polyphenyl
derivatives such as hydrogenated terphenyl; citric acid derivatives, such
as triethyl citrate, tri-n-butyl citrate, acetyl triethyl citrate, acetyl
tri-n-butyl citrate, acetal tributyl citrate; epoxy derivatives such as
butyl epoxy stearate, epoxy-type plasticizer, epoxy-type plasticizer
tallate, alkyl epoxy stearate, epoxidized butyl ester, epoxidized octyl
tallage, epoxidized soybean oil, epoxidized triglyceride, epoxidized soya
bean oil, epoxidized sunflower oil, epoxidized-type plasticizer,
epoxidized linseed oil, epoxidized tallate ester, 2-ethylhexyl-epoxy
tallate, octyl epoxy stearate; proprietary esters such as proprietary
ester and mixed ester; ether derivatives, such as cumylphenyl benzyl
ether; formal derivatives such as 2-(2-butoxyethoxy)ethanal; fumaric acid
derivatives, such as dibutyl fumarate, diisooctyl fumarate, dioctyl
fumarate; glutaric acid derivatives such as mixed dialkyl glutarates and
dicumylphenyl glutarate; glycol derivatives such as diethylene glycol
dipelargonate, triethylene glycol dipelargonate, triethylene glycol
di-(2-ethyl butyrate), triethylene glycol di-caprylate-caprate,
triethylene glycol di-(2-ethylhexoate), triethylene glycol dicaprylate,
tetraethylene glycol dicaprylate, polyethylene glycol di-(2-ethylhexoate),
butyl phthalyl butyl glycolate, triglycolester of vegetable oil fatty
acid, triethylene glycol ester of fatty acid; linear dibasic acid
derivatives such as mixed dibasic ester; petroleum derivatives such as
aromatic hydrocarbons; isobutyric acid derivatives such as
2,2,4-trimethyl-1,3-pentanediol diisobutyrate; isophthalic acid
derivatives such as di(2-ethylhexyl) isophthalate, diisooctyl
isophthalate, dioctyl isophthalate; lauric acid derivatives such as
butyllaurate, 1,2-propylene glycol monolaurate, ethylene glycol monoethyl
ether laurate, ethylene glycol monobutyl ether laurate, glycerol
monolaurate, polyethylene glycol-400-dilaurate; mellitates such as
n-octyl, n-decyl trimellitate, tri-n-octyl-n-decyl trimellitate,
triisononyl trimellitate, triisooctyl trimellitate, tricapryl
trimellitate, diisooctyl monoisodecyl trimellitate, triisodecyl
trimellitate, tri(C.sub.7-9 alkyl) trimellitate, tri-2-ethylhexyl
trimellitate; nitrile derivatives such as fatty acid nitrile; oleic acid
derivatives such as butyl oleate, 1,2-propylene glycol mono oleate,
ethylene glycol monobutyl ether oleate, tetrahydrofurfuryl oleate,
glyceryl monoleate; paraffin derivatives such as chlorinated paraffins,
diethylene glycol dipelargonate, triethylene glycol dipelargonate,
2-butoxyethyl dipelargonate; phenoxy plasticizers such as acetyl paracumyl
phenol; phosphoric acid derivatives such as tri-(2-ethylhexyl) phosphate,
tributoxyethyl phosphate, triphenyl phosphate, cresyl diphenyl phosphate,
tricresyl phosphate, tri-isopropylphenyl phosphate, alkyl aryl phosphates,
diphenyl-xylenyl phosphate, phenyl isopropylphenyl phosphate; phthalic
acid derivatives such as alkyl benzene phthalates, dimethyl phthalate,
dibutyl phthalate, diisobutyl phthalate, dihexyl phthalate, butyl octyl
phthalate, butyl isodecyl phthalate, butyl ISO-hexyl phthalate, diisononyl
phthalate, dioctyl phthalate, di-(2-ethyl hexyl) phthalate,
n-octyl-n-decyl phthalate, hexyl octyl decyl phthalate, didecyl phthalate
diisodecyl phthalate, diisodecyl phthalate, diundecyl phthalate,
butyl-ethylhexyl phthalate, butylbenzyl phthalate, octylbenzyl phthalate,
dicyclohexyl phthalate, diphenyl phthalate, alkylaryl phthalates and
2-ethylhexylisodecyl phthalate; ricinoleic acid derivatives such as
methylacetyl ricinoleate, n-butyl acetyl ricinoleate, glyceryl triacetyl
ricinoleate; sebacic acid derivatives such as dimethyl sebacate, dibutyl
sebacate, and dibutoxyethyl sebacate; stearic acid derivatives such as
glyceryl tri-acetone stearate, butyl acetoxy stearate,
methylpentachlorostearate, and methoxylethyl acetoxy stearate; sucrose
derivatives such as sucrose benzoate; sulfonic acid derivatives such as
alkyl-sulfonic esters of phenol; tall oil derivatives such as methylester
of tall oil and isooctyl ester of tall oil; and terephthalic acid
derivatives such as dioctyl terephthalate.
Such leathery compositions typically contain from about 40 to 160 parts by
weight of the rubbery polymer, from about 10 to about 50 parts of a
plasticizer and from about 0.1 to about 5 parts by weight of an
antidegradant per 100 parts by weight of the polyvinylchloride. It is
typically preferred for such leathery compositions to contain from about
60 to about 120 parts by weight of the rubbery polymer, from about 15 to
about 40 parts of the plasticizer and from about 0.5 to 3 parts of an
antidegradant (per 100 parts of the PVC). It is typically more preferred
for the leathery composition to contain from about 70 to about 90 parts by
weight of the rubbery polymer, from about 20 to about 30 parts by weight
of the plasticizer and from about 1 to 2 parts by weight of the
antidegradant per 100 parts by weight of the PVC.
Such compositions will also generally contain an
acrylonitrile-butadiene-styrene resin (ABS resin). The leathery
composition will typically contain from about 15 parts to about 80 parts
of ABS resin per 100 parts of PVC. The leathery composition will
preferably contain from about 25 to about 55 parts per weight of the ABS
resin per 100 parts by weight of the PVC. It is generally more preferred
for the leathery composition to contain from about 30 to about 40 parts by
weight of the ABS resin per 100 parts by weight of PVC. Various colorants
and/or pigments will typically also be added to the composition to attain
a desired color.
The leathery compositions of this invention are useful in a wide variety of
applications. For example, they have been found to be extremely valuable
when used in making skins for automotive panels. Such panels are typically
comprised of a semi-rigid urethane foam which is supported by a rigid
backing and covered with the leathery composition of this invention. Such
skins are made by calendering the leathery compositions of this invention
and then cutting them to the desired size and shape. Such skins for
automotive applications which are made with the leathery compositions of
this invention offer outstanding heat and ultraviolet light stability.
These are highly desirable characteristics which can help to prevent the
skin of automotive panels from cracking during the normal life of the
vehicle.
The rubbery polymers of this invention can also be blended with other
halogen containing polymers (in addition to PVC), styrenic polymers
(polymers which contain styrene, such as acrylonitrile-styrene-acrylate
(ASA) polymers), polyolefins and polyamides to produce compositions which
exhibit good heat and ultraviolet light resistance. Such polymeric
compositions can be used in manufacturing a wide variety of useful
articles, such as profiles, moldings, sheeting, flooring, wall coverings,
hose, cables, footwear, automotive instrument panels and automotive door
panels. Virtually any type of polyamide (nylon) can be utilized in
preparing such blends. These nylons are generally prepared by reacting
diamines with dicarboxylic acids. The diamines and dicarboxylic acids
which are utilized in preparing such nylons will generally contain from
about 2 to about 12 carbon atoms. However, nylons that can be utilized in
such blends can also be prepared by addition polymerization. Some
representative examples of nylons which can be used include nylon-6,6,
nylon-6, nylon-7, nylon-8, nylon-9, nylon-10, nylon-11, nylon-12 and
nylon-6,12. These nylons will typically have a number average molecular
weight which is within the range of about 8,000 to about 40,000 and will
more typically have a number average molecular weight which is within the
range of about 10,000 to about 25,000. Some representative examples of
polyolefins that can be used include linear low density polyethylene, high
density polyethylene, polypropylene, polybutylene and modified
polyolefins, such as ethylene vinyl acetate (EVA).
This invention is illustrated by the following examples that are merely for
the purpose of illustration and are not to be regarded as limiting the
scope of this invention or the manner in which it can be practiced. Unless
specifically indicated otherwise, all parts and percentages are given by
weight.
EXAMPLE 1
In this experiment, a rubbery polymer was made utilizing the techniques of
this invention. The polymerization was conducted in a reactor having a
capacity of 10 gallons (37.85 liter). The reactor was equipped with two
axially flow turbine agitators with baffles which were operated at 150 rpm
(revolutions per minute). A buffer solution was made by mixing 339 grams
of a 25 percent aqueous solution of dodecylbenzenesulfonate, 56.5 grams of
tetrasodium pyrophosphate and 33.9 grams of potassium persulfate into
16.96 kg of water. A first monomer solution was made by mixing 9.04 kg of
butyl acrylate, 904 grams of acrylonitrile, 452 grams of methyl
methacrylate, 226 grams of ethylene glycol dimethacrylate, 28.25 grams of
tertiary-dodecyl mercaptan and 904 grams of 1,3-butadiene, and a second
monomer solution was made by mixing 1.22 kg of styrene, 548 grams of
acrylonitrile, 11.3 grams of tertiary-dodecyl mercaptan, 113 grams of a 55
percent solution of divinylbenzene and 226 grams of 1,3-butadiene.
The reactor was evacuated for 30 minutes and then the buffer solution was
introduced into the reactor. The first monomer solution was then charged
into the reactor and the polymerization medium was maintained at a
temperature of 120.degree. F. (49.degree. C.). When the solids content of
the latex reached 40 percent, the second monomer solution was charged into
the reactor and the temperature of the polymerization medium was increased
to 175.degree. F. (80.degree. C.). After the solids content reached 43-45
percent, the temperature was maintained at 175.degree. F. (80.degree. C.)
for an additional 4 hours to insure that a high conversion had been
attained.
A 2000-gram sample of the latex synthesized was subsequently epoxidized by
slowly adding 15 grams of formic acid and 10 grams of acetic acid in 200
mls of water to the sample. Then, 70 grams of a 35 percent solution of
hydrogen peroxide was stirred into the latex. The latex containing the
formic acid, the acetic acid and the hydrogen peroxide was then put in a
jug and placed in an oven at 110.degree.-120.degree. F.
(43.degree.-49.degree. C.) for 3-4 hours. Then, 37 grams of Aquamix 192
antioxidant was added and the latex was coagulated. The rubbery polymer
recovered was washed twice and dried. The rubbery polymer synthesized in
this experiment contained about 10 percent bound butadiene monomer.
EXAMPLE 2
In this experiment, a rubbery polymer containing 8 percent bound butadiene
was synthesized utilizing the technique of this invention. The procedure
described in Example 1 was repeated in this experiment except that the
amount of 1,3-butadiene employed in making the first monomer solution was
decreased to 678 grams with the amount of butyl acrylate employed in
making the first monomer solution being increased to 9.266 kg. The latex
synthesized was also epoxidized and recovered utilizing the procedure
described in Example 1.
EXAMPLE 3
In this experiment, a rubbery polymer containing 4 percent bound butadiene
was synthesized utilizing the technique of this invention. The procedure
described in Example 1 was repeated in this experiment except that the
amount of 1,3-butadiene employed in making the first monomer solution was
decreased to 339 grams with the amount of butyl-acrylate employed in
making the first monomer solution being increased to 9.605 kg. In this
experiment, the amount of 1,3-butadiene employed in making the second
monomer solution was also decreased to 339 grams with the amount of butyl
acrylate employed in making the second monomer solution being increased to
9.605 kg. The latex synthesized was also epoxidized and recovered
utilizing the procedure described in Example 1.
The rubbery polymer sample was clear. In fact, the rubbery polymer had
sufficient clarity to allow print having 6-point font to be read through a
0.125-inch (3.175 mm) thick sheet of said rubbery polymer. More
specifically, the rubbery polymer had sufficient clarity to allow the word
"clear" printed in black letters on a white background using 6-point type
to be read through a 0.125-inch (3.175 mm) thick sheet of the rubber with
the unaided eye under typical indoor illumination.
EXAMPLE 4
The rubbery polymer synthesized in Example 2 was compounded into a standard
crash pad formulation and evaluated for color stability. It was also
compared to a standard crash pad formulation made with a rubbery polymer
having the same composition that had not been epoxidized. The light aging
studies were conducted in a Q-U-V accelerated weathering tester that was
equipped with a UVB-313 lamp. One aging cycle consisted of 6 hours of
light and 4 hours of 100 percent humidity at 65.degree. C. with continuous
repeated cycles to a total of 500 hours. The crash pad formulation made
utilizing the rubbery polymer synthesized in Example 2 showed a Delta E
color change of only about 2.5. The crash pad formulation made utilizing
the comparative polymer showed a Delta E color change of about 7. Thus,
the crash pad formulation made utilizing the rubbery polymer of this
invention showed much better color stability.
EXAMPLE 5
In this experiment, a rubbery polymer was synthesized utilizing the
polymerization procedure described in Example 3. However, the latex made
was ozonated rather than epoxidized. This was accomplished by simply
introducing ozone into the latex sample. After the ozonalysis had been
completed, the rubbery polymer samples were recovered and dried as
described in Example 1.
Heat aging was conducted by the ASTM 573-78 air oven heat aging method with
ASTM die C specimens. Tensile properties were determined before and after
aging with a United Model FM30-DM1VA tensile tester at 20 inches per
minute (50.8 cm/minutes) crosshead speed, 2.5 inch (6.35 cm) jaw
separation and 1 inch (2.54 cm) benchmark. For comparative purpose, a
sample of rubbery polymer made without incorporating a conjugated diolefin
monomer therein was also evaluated. Since this comparative rubber did not
contain double bonds, it was not ozonated.
______________________________________
Elongation vs. Heat Aging Time
Heat Aging Time
Ozonated Rubber
Comparative Rubber
______________________________________
Original 158% 89%
70 hours 181% 121%
144 hours 157% 116%
288 hours 147% 127%
384 hours 143% 124%
480 hours 115% 70%
528 hours 125% 98%
______________________________________
As can be seen from the table above, the ozonated rubbery polymers had much
better elongation characteristics than did their non-ozonated
counterparts. This experiment accordingly shows that the ozonalysis
technique of this invention can be used to improve the tensile properties
of the rubbery polymers described herein.
While certain representative embodiments and details have been shown for
the purpose of illustrating the subject invention, it will be apparent to
those skilled in this art that various changes and modifications can be
made therein without departing from the scope of the subject invention.
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